Gas blast electric circuit breaker



Match 10, 1942.

H. TRENCHAM ETAL GAS BLAST ELECTRIC CIRCUIT BREAKER Filed June 19, 1940 2 Sheets-Sheet 1 I nven COPS 1 MW n CC l wsawm m c xw m WmHWW H Marhl0, 1942. H T RE HAM ETA 2,275,872

GAS BLAST ELECTRIC CIRCUIT BREAKER Filed June 19, 1940 2 'Sheets-Sheet 2 Inventors:

' Henry Trencham Harald E, Cox,

Their AttQ v-wey.

Patented Mar. 10, 1942 GAS BLAST ELECTRIC CIRCUIT BREAKER Henry 'Ireneham, Ruialip, and Harold Ernest Cox, Dollis Hill, London, England, assignots to General Electric Com New York pany, a corporation of Application June 19, 1910, Serial No. 341,392

I In Great Britain June 27, 1939 Claims.

This invention relates to circuit breakers for use in alternating current electric power systems especially those wherein a fiuid blast is used for the extinction of the are.

It is known to provide for the insertion of a resistance in series with a portion of the are formed during the opening operation of circuit breakers and that such a measure provides a means for dealing effectively with circuits having a high rate of rise of restriking voltage. This feature is of particular use on gas or air blast circuit breakers wherein the inherent ability to deal with circuits of high severity is not great. It has been proposed to eflect the insertion of the resistance in circuit breakers of the fluid blast type using an extinguishing nozzle by providing an auxiliary electrode in the throat of the nozzle or immediately behind the throat, this electrode forming a contact to which one terminal of the resistance is connected,-the other terminal being connected to one of the main contacts, but this arrangement involves undesirable constructional complications.

The object of the present invention is to provide means for introducing the resistance in a more convenient and effective manner.

According to the invention, the resistance is connected in shunt with the are initially formed .on opening the breaker under load by connecting it between the main fixed contact and an auxiliary contact insulated from the fixed contact and located so as to be engaged by the movable contact in its passage towards the fixed contact in moving to closed circuit position.

- The accompanying drawings illustrate in section portions of a complete gas blast breaker sufiicient to enable the nature of the invention to be readily understood; Fig. 1 showing one form of construction, Figs. 2 and 3 details of the construction-shown in Fig. 1, and Figs. 4 and 5 modified arrangements.

In carrying out the invention, the main fixed contact is preferably of nozzle-shape formation,

such as shown at 3 in Fig. 1, and is adapted to be engaged by a movable contactin the form of a rod or tube I. contacts may, however, make buttengagement with one another. In one arrangement the gas blast is introduced between the contactsin such a manner (by providing inlet and exhaust openings-on opposite sides of an insulating tube 4 in which the movable contact moves and which The main fixed and movable supports the fixed contact at one end) that the to the axis of the movable contact. The gas blast may be directed across the are by means of an arc extinguishing structure generally indicated at 5 comprising a plurality of discs of insulating material stacked together and mounted in the insulating tube between the inlet and exhaust openings, and shaped to provide separate blast passages on either side oi an arc splitter member incorporating the auxiliary contact at I I.

Referring more specifically to Fig. 1 of the drawings the main current is carried by means of an axially moving contact rod or tube I, which is surrounded near its lower end by a garter type of sliding contact (not shown) and engaging at its upper end with a fixed contact 2 of similar type. The contact 2 is supported in and electrically connected to a nozzle shaped member 3. The arc extinguishing medium as for example compressed air, is introduced into a cylinder 4 of insulating material which surrounds the main contact rod, and supports at its upper end the member 3 and at an intermediate position an arc extinguishing nozzle structure 5, which is adapted to direct the gas blast transversely of the path of movement of contact I from an inlet conduit 6 to an exhaust passage 1. The nozzle structure is preferably built up from discs '8 of fibre, shown in plan in Fig. 2, separatlngmembers 9, and at least one splitter member Ill shown in plan view in Fig. 3. A metal contact H which may be in the form of a flatring is carried by the splitter member "I and is used as an electrode for connecting to one end of a V resistance I2, the other end of which is connected to the main fixed contact.

In the circuit interrupting operation therefore, the first portion of the movement of the contact rod I disengages it from the main contact 2,

introducing the resistance and at the meme allowing the gas or air blast to pass acrossthe arcing space. Further movement diseng m the contact rod from the electrode H carried by the splitter member whilst leaving the extinguishing blast 'inoperation onboth the main and resistance breaks. v

The blast of extinguishing gas or air may' be supplied as shown to the cylinder surrounding the contact rod at a point on its length opposite to or adjacent to the venting orifice, or may be introduced further down the same tube at apointadjacent to-the surrounding garter type of contact. In a further variation the garter type contact at the lower end of the contact contact carried in the pressurehead. In another arrangement shown by Fig.4, the

gas blast fiows mainly along the path of the arc movable contact has separated a predetermined distance from the fixed contact. i

In the construction shown in Fig. 5, the movable contact'l is made hollow at its upper end formed between the rod-like movable contact I-- and a nomle-shape orifice forming part of the fixed contact structure I and carried in an insulating tube 4 in which the movable contact slides, the pressure gas being introduced through an inlet opening as at located in the side of the tube. In this arrangement the auxiliary electrode I l is arranged to make contact laterally with the movable contact by allowing it to project the contact I so as to be engagedby-that contact as it moves into engagement with contact I. The electrode II is connected as in the arrangement of Fig. 1, to the contact I through the' resistance It. The inside end of electrode ll may have a coating of insulation to prevent the are from wandering to its outer wall surface.

The operation of the circuit breaker in opening is as follows: In the closed position current passes from the lower garter type contact l4 into the contact rod and thence from the top fixed socket contact, the resistance passing no current. when the contact rod moves down out and engages the fixed contact 2 which is made withthe nozzle-shaped part I forming an exhaust. blast passage as in the above described arrangements. 1 The insulating tube 4 'is closed near its lower end by .the barrier l4 having a central aperture suiilcient to allow the movable contact to pass through it. The barrier I4 and the fixed contact structure I are sufilciently spaced as shown to form with the insulating contact I.

of engagement with the socket contact the main current are. is forced into the the tubular electrode. rurther'movement of the contact rod draws itclear of the tubular elece comprisedin this contact and is extinguished leaving current fiowing through the resistance element via nozzle for the resistance current.

It may be provided that in the completely open position, the contact rod is withdrawn from the insulating pressure cylinder in order that a clear isolating gap may exist between the main terminals. I

According to a further feature of-the invention shown by Fig. 5, the movable contact I is made hollow and the gas blast is caused to fiow both through the hollow movable contact and through an orifice in the fixed contact structure during the movement of the contact away from the fixed contact structure. The arc formed between the auxiliary electrode .and the movable contact is then extinguished by the flow of pressure gas through the hollow contact. The movable contact may, in this case, be hollow throughout its length, but is preferably made hollow as shown onlyat the end adjacent to the fixed contact structm'e, being then provided with side orifices such as at, through the wall at a point away from the contacting end. The orifices are are initially covered by means associated with preferably located at a position such that they tube 4 an interrupting chamber. In the open position of the breaker the movable contact completely withdraws from the interrupting chamber and tube 4 givingan air isolating break between the lower end of the tube 4 and, the contact I. The lowergarter contact for the movable contact I is not shown.

- In the circuit opening operation compressed gas is introduced through the inlet conduit 0 and flows through the annular space ll between the tube 4 and the fixed nozzle-shaped part I into the interrupting chamber and as the contact I is lowered, fiows upwardly through the nozzleshaped opening at 3 for extinguishing the arc. The gas blast also flows from the interrupting chamber downwardly through the hollow contact I to exhaust through the side orifices II which are then uncovered by the barrier 14' owing to the movement of As the contact I leaves the contact 2 the resistance It is connected in shunt with the initial arc, and"as the contact I leaves the auxiliary electrode H the secondary arc formed between contact I and the electrode H is extinguished by the downward fiow of gas through the hollow centre of contact I. It will therefore be seen that the arc is acted upon by two oppositely directed gas blasts from the interrupting chamber, one portion of the are adjacent to the fixed hollow contact 2 being subjected to the blast flowing-upwardly into the exhaust blast passage at I and another portion of the arc being subjected to the blast fiowing downwardly through the movable hollow contact I. The main are between the contacts 2 and I is thus acted upon by twooppositely directed gas blasts while in the interrupting chamber, and in case the circuit is still uncleared the lower portion of the are then attaches to the auxiliary electrode H to insert theresistancell. for facilitating final interruption by the blast through the hollow contact i.

It should be understood that our invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled inv the art without departing from the spiritof our invention.

What we claimas new, and desire to secure by Letters Patent of the United States is:

1. A gas blast circuit breaker comprising a fixed hollow contact forming a blast passage, a movable contact co-operating with said fixed contact, a hollow tubular insulating member for supporting said fixed contact and guiding-said movable contact into co-operating relation therewith.

tween said movable and fixed contacts and into said blast passage as they separate under load, an auxiliary contact disposed adjacent to the path of movement of said movable contact and adapted to make contact therewith as said movable contact moves towards or away from said fixed contact, a resistance connected between said fixed and auxiliary contacts, and an arc extinguishing structure also forming a blast passage disposed adjacent to said auxiliary contact for directing an auxiliary gas blast thereacross.

2. A gas blast circuit breaker comprising a fixed hollow contact forming a blast passage, a movablehollow contact co-operating with said fixed contact, a hollow tubular insulating memher for supporting said fixed contact and guiding saidmovable contact; into co-operating relation therewith, means for moving said movable contact into and out of engagement with said fixed contact, an inlet aperture in said tubular member for introducing pressure gas thereinto, said gas flowing out of said tubular member through said fixed and movable contacts and through saidblast passage when they are separated, an auxiliary contact disposed adjacent to the path of movement of said movable contact and adapted to make contact therewith as said movable contact moves towards or away from said fixed contact, and a resistance connected between said fixedand auxiliary contacts, said hollow movable contact forming a gas blast passage adjacent to said auxiliary contact for also directing a gas blast thereacross.

3. A gas blast circuit breaker comprising an interrupting chamber, relatively movable contact structure separable to form an arc gap in said chamber, said relatively movable contact structure forming gas exhaust passages leading in opposite directions from said chamber, means for directing an interrupting gas under pressure into said chamber, means for causing separation of said contact structure so that one portion of the are within said chamber is subjected to a gas blast ture, the are at said conducting means being subjected to said last-named gas blast.

4, A gas blast circuit breaker comprising an interrupting chamber, relatively fixed and movable contacts separable to form an arc gap in said chamber, said relatively movable contacts forming gas exhaust passages leading in oppo site directions from end walls of said chamber, means for directing an interrupting gas under pressure into said chamber, means for causing separation of said contacts so that the portion of the arc within said chamber at said fixed contact is subjected to a gas blast exhausting through 4 the fixed contact passage, and the portion of the are at said movable contact is subjected to another gas blast exhausting in the opposite direction through the movable contact passage, and fixed conducting means positioned in said chamher in sliding conducting engagement with said movable contact to which the arc attaches as said movable contact is being withdrawn from said chamber, the arc at said fixed conducting means being subjected to said last-named gas blast.

5. A gas blast circuit breaker-comprising an interrupting chamber, relatively fixed and movable hollow contacts separable to form an arc gap in said chamber, said hollow contacts forming gas exhaust passages leading from opposite ends of said chamber, means for directing an interrupting gas under pressure into said chamber, means for causing separation of said contacts so that the are at said fixed contact within said chamber is subjected to a gas blast exhausting upwardly through said fixed contact passage, and the are at said movable contact is subjected to another gas blast exhausting downwardly in the opposite direction through the movable contact passage, and conducting structure'positioned in said chamber in spaced relation to said fixed contact and in close electrical relation to said movable contact so that the arc attaches to said conducting structure from said movable contact as it is being withdrawn from said chamber 

